ANSWER: The most difficult part of building the web is the first strand, which will form a bridge between the two poles. The spider makes the bridge by releasing a length of sticky thread and "kiting" – letting the thread blow in the breeze. With a bit of luck, it will catch on another object. When the spider feels the thread catch onto something, it pulls it tight and attaches it to the starting point.

Next, the spider walks the high wire, using special claws to grip the thread. As it does so, it releases a slack thread beneath the bridge thread.

Once the slack thread is attached to the other side, the spider will usually climb back to the middle of it, lower itself and attach it to some object to form a Y-shape. This strategy will not work between the poles, so the spider will have to attach it to a spot lower on the pole, either by kiting or by climbing down the pole.

Once the difficult main support structure of the web is in place, the spider can complete the frame, add radius threads from the frame to the center of the web and create a spiral from the center to the frame.

Incidentally, the spider you saw was likely a golden garden spider or another of the three local species of Argiope orb weavers. When they mature in late summer and early fall, it is difficult to miss the large females (males are much smaller) on the center of their magnificent webs.

Baking soda does a remarkable job of neutralizing foul odors. How does it work?

– Mort Tuchin, Poway

Many unpleasant odors, such as those associated with vinegar, sour milk and rotten eggs, are acidic molecules. Baking soda – sodium bicarbonate – is a weak base that can react chemically with acids to neutralize them. It can also react with a stronger base, so baking soda also neutralizes the basic molecules that cause fishy or ammonia smells.

The reaction between the baking soda and odor molecules is not visible, because not many molecules react at once. However, you can see the reaction if you mix vinegar and baking soda. The gas that bubbles off is carbon dioxide, which is formed during the reaction.

This is the reason you may burp when you take antacids. Antacids are usually made of calcium carbonate, but their reaction with stomach acids is similar to the vinegar-baking soda reaction.

Sherry Seethaler has a doctorate in science education and is a UCSD science writer and educator. Send your scientific questions to her at Quest, The San Diego Union-Tribune, P.O. Box 120191, San Diego, CA 92112-0191. Or e-mail sseethaler@ucsd.edu. Please include your name, city of residence and phone number.